linux-kernel - RE: (ondemand) CPU governor regression between 2.6.23 and 2.6.24

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Date:	Mon, 4 Feb 2008 09:44:24 -0800
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	"Andrew Morton" <akpm@...ux-foundation.org>,
	Toralf Förster <toralf.foerster@....de>
Cc:	<linux-kernel@...r.kernel.org>, <cpufreq@....linux.org.uk>
Subject: RE: (ondemand) CPU governor  regression between 2.6.23 and 2.6.24

 

>-----Original Message-----
>From: linux-kernel-owner@...r.kernel.org 
>[mailto:linux-kernel-owner@...r.kernel.org] On Behalf Of Andrew Morton
>Sent: Sunday, February 03, 2008 4:33 PM
>To: Toralf Förster
>Cc: linux-kernel@...r.kernel.org; cpufreq@....linux.org.uk
>Subject: Re: (ondemand) CPU governor regression between 2.6.23 
>and 2.6.24
>
>On Sat, 26 Jan 2008 15:06:25 +0100 Toralf Förster 
><toralf.foerster@....de> wrote:
>
>> I use a 1-liner for a simple performance check : "time 
>factor 819734028463158891"
>> Here is the result for the new (Gentoo) kernel 2.6.24:
>> 
>> With the  ondemand governor of the  I get:
>> 
>> tfoerste@n22 ~/tmp $ time factor 819734028463158891
>> 819734028463158891: 3 273244676154386297
>> 
>> real    0m32.997s
>> user    0m15.732s
>> sys     0m0.014s
>> 
>> With the ondemand governor the CPU runs at 600 MHz,
>> whereas with the performance governor I get :
>> 
>> tfoerste@n22 ~/tmp $ time factor 819734028463158891
>> 819734028463158891: 3 273244676154386297
>> 
>> real    0m10.893s
>> user    0m5.444s
>> sys     0m0.000s
>> 
>> (~5.5 sec as I expected) b/c the CPU is set to 1.7 GHz.
>> 
>> The ondeman governor of previous kernel versions however 
>automatically increased
>> the CPU speed from 600 MHz to 1.7 GHz.
>> 
>> My system is a ThinkPad T41, I'll attach the .config 
>> 
>

This looks like is related to the report here
http://www.ussg.iu.edu/hypermail/linux/kernel/0801.3/1260.html

Can you try the workarounds on that thread and see whether the problem goes away.

Thanks,
Venki
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